I haven't found a wall mounted sliding mechanism especially designed for artist easels in the prior art. There are similar products which are quite common that use this sliding mechanism within a casing, but are quite a bit more complicated than my embodiment. The main disadvantage is the extra costs involved in a more complicated design.
The prior art I found relating to similar sliding mounting devices are by Ann Marie Reo, Chantal Louise Pittman, Brian Scott Jalufka—Wall mounting bracket U.S. Pat. No. 8,474,770 B2 (Jul. 2, 2013); Wen-Chun Chen, Ming-Chin Huang Wall mounting monitor bracket U.S. Pat. No. 7,448,584 B2 (Nov. 11, 2008); —Sliding Wall-Mount chassis CN102781195 B (Apr. 1, 2015); Mike David—Wall Bracket with integrated vertical lock US20090206214 A1 (Aug. 20, 2009); Zen Vic De—Support and Attachment Wall Mount assembly CA 2245809 A1 (Feb. 27, 2000); Manuel Saez—Mechanism for Positional Adjustment of an Attached Device US 20130248670 A1 (Sep. 26, 2013); William Dubon and Ronan Stephens—US Telescoping Slide Assembly U.S. Pat. No. 6,938,967 B2 (Sep. 6, 2005); Keith A. Hoffman—Recyclable Drawer Slide U.S. Pat. No. 5,411,333 (May 2, 1995); Maxwell Scott Fall, William B. Greenwald, Carl Edward Hansen—Telescoping Slide with Quick-Mount System U.S. Pat. No. 6,209,979 B1 (Apr. 3, 2001); Mo-Ming Yu, Guang-Hua Gu, Ze-Hong Chen—Slide Assembly U.S. Pat. No. 8,235,479 B2 (Aug. 7, 2012); Shulyan Chen, Xin Su, Steven Chen—Slide Rail Assembly and Slide Rail Assembly Pair U.S. Pat. No. 9,560,786 B2 (Jan. 31, 2017); R. C. Trainor—Adjustable Support for Mirrors U.S. Pat. No. 2,569,622 (Oct. 2, 1951)—are all different in their scope, design and function from my embodiment and not especially designed for an artist easel. The art that Manual Saez teaches US 20130248670 A1 comes close to my embodiment, however I don't claim a “plurality of motion regulating devices”—specifically the gas spring shaft (60) and gas spring chamber (65) to adjust the position of the attached device. I just have pressure plates to fix the position of the easel arm. Saez's embodiment is designed for a computer display or flat screen monitor. My embodiment is especially designed to work with the 360 Degree Rotational Easel patented by the same inventor Robert A. Selwa U.S. Pat. No. 9,220,330 B, with issue date Dec. 29, 2015.